Osteoarthritis in Cats: More Common Than You Think
Thanks to the marvels of modern veterinary medicine, our pets are living much longer lives. With longer lives, however, come chronic diseases such as osteoarthritis. Osteoarthritis is a commonly recognized disease in dogs. Until recently, however, it was less commonly diagnosed in cats. Fortunately, veterinarians are now more aware of this problem in older cats and are helping them live less painful lives.
Osteoarthritis is a degenerative condition of the joints in which the normal cartilage cushion in the joints breaks down.1 Eventually, the bones in the joint rub against each other, causing pain, decreased joint movement, and sometimes the formation of bone spurs or other changes in and around the joint.2 Osteoarthritis continues to get worse over time; however, it can be managed so that the progress of the disease is slowed down, helping the joint to work as well as possible for as long as possible.
Diagnosing osteoarthritis in cats is difficult even for experienced veterinarians. Cats, unlike most dogs, can tolerate bone and joint problems due to their small size and natural agility. They also generally dislike being physically handled during examinations. Your veterinarian may have a hard time deciding whether your cat is pulling its foot away because of pain or simply because it doesn’t want to be touched.3 Cats are notorious for cowering on the exam table and not moving. As a result, a cat owner’s observations about his cat's decreased activity becomes very important if the veterinarian suspects the cat may have osteoarthritis. Veterinarians that suspect osteoarthritis may treat their cat patients for osteoarthritis to see if they show any improvement.
In cats, changes in affected joints are usually subtle. Decreased range of joint motion, commonly seen in dogs, is uncommon in cats.4 Crepitus, a grinding, crunching sound or feeling in a joint, is also common in dogs, but is uncommon in cats. Thickening of the tissues around and inside of affected joints, however, is a common finding.5
Clinical signs of osteoarthritis in cats include weight loss, loss of appetite, depression, change in general attitude, poor grooming habits, urination or defecation outside the litter pan, and inability to jump on and off objects.6 Surprisingly, lameness is not as commonly reported a clinical sign by owners as you might expect. Because the same joints are often affected on both sides of a cat's body, a cat can compensate and appear to be walking normally.7 In a study, only 43 percent of cats were described to be limping, while 71 percent were unwilling to jump, and 67 percent had shorter jumps.8
The most frequently-affected joints in cats are the elbows and hips, although shoulders and hocks (ankles) have also been reported.9 Arthritis in the backbone and sternum is also common.10
Researchers have conducted studies looking at changes in radiographs associated with osteoarthritis in cats. In general, radiographic changes in cats with osteoarthritis are less severe than those in dogs with osteoarthritis. Sometimes, cats with osteoarthritis have no radiographic changes.11, 12
A study in the Journal of Veterinary Internal Medicine looked at the association between radiograph and physical exam findings in 13 cats with osteoarthritis. Researchers examined the cats' joints for evidence of pain and/or radiographic changes seen with osteoarthritis. Half of the cats' joints they examined had osteoarthritis. Only 10% of the joints, however, had both clinical pain and radiographic changes.13 Painful joints, therefore, don't necessarily agree with the changes seen on the radiographs.
Treatment options for cats with osteoarthritis are limited. Non-drug treatment options include weight loss for overweight cats, increased exercise, and environmental accommodations, like using litter pans with lower sides for ease of entering and exiting, elevating food and water bowls, and providing soft bedding.14 For pain relief, steroids have been used in the past; however, they have fallen out of favor due to side effects.15 The only approved non-steroidal anti-inflammatory drugs (NSAIDs) for use in cats are Metacam® 5 mg/mL Solution for Injection, Loxicom 5 mg/mL Solution for Injection, Meloxicam 5 mg/mL Solution for Injection, Onsior 6 mg Tablets, and Onsior Injection. Metacam® Solution for Injection, Meloxicam Solution for Injection, and Loxicom Solution for Injection are approved for a one-time dose for the control of postoperative pain associated with orthopedic surgery, ovariohysterectomy (spay surgery), and castration (neuter surgery) in cats. They are not approved for any repeat dosing. Onsior 6 mg Tablets are approved only for a maximum of three days’ duration for the control of postoperative pain and inflammation associated with orthopedic surgery, ovariohysterectomy (spay surgery), and castration (neuter surgery) in cats. Neither Onsior Tablets nor Onsior Injection should be used in cats under 4 months of age. Onsior Tablets should not be used in cats weighing less than 5.5 lbs. Unfortunately, no veterinary NSAIDs are currently approved for safe, long-term control of osteoarthritis pain in cats. More information about veterinary NSAIDs can be found in the article, Get the Facts about Pain Relievers for Pets.
Osteoarthritis in cats is difficult even for the experienced veterinarian to diagnose. By knowing what common signs to look for, pet owners like you can provide important clues for their veterinarians. This information, along with physical examination radiographic evidence, and new methods of pain assessment, can help veterinarians better diagnose the disease and more readily ease the silent suffering of many older cats.
2National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) of the National Institutes of Health. Fast Facts: An Easy-to-Read Series of Publications for the Public--What is Osteoarthritis? November 2014. https://www.niams.nih.gov/sites/default/files/catalog/files/osteoarthritis_ff.pdf
3Clarke SP and Bennett D. Feline osteoarthritis: a prospective study of 28 cases. 2006. Journal of Small Animal Practice. 47(8):439-445.
6Hardie EM. Management of osteoarthritis in cats. 1997. Veterinary Clinics of North America: Small Animal Practice. 27(4):945-953.
8Clarke and Bennett, pp. 439-445.
10Clarke SP, Mellor D, Clements DN, et al. Prevalence of radiographic signs of degenerative joint disease in a hospital population of cats. 2005. Veterinary Record. 157:793-799.
11Godfrey DR. Osteoarthritis in cats: a retrospective radiological study. 2005. Journal of Small Animal Practice. 46:425-429.
12Hardie EM, Roe SC, and Martin FR. Radiographic evidence of degenerative joint disease in geriatric cats: 100 cases (1994-1997). 2002. Journal of the American Veterinary Medical Association. 220:628-632.
13Lascelles BDX, Hansen BD, Roe S, et al. Evaluation of client-specific outcome measures and activity monitoring to measure pain relief in cats with osteoarthritis. 2007. Journal of Veterinary Internal Medicine. 21(3):410-416.
14Hellyer P, Rodan I, Downing R, et al. AAHA/AAFP pain management guidelines for dogs and cats. 2007. Journal of the American Animal Hospital Association. 43:235-248.
15Caney S. Feline Arthritis. 2007. Veterinary Focus. 17(3):11-17.